Traffic actuated control system



J. L. BARKER 3,128,446 I TRAFFIC ACTUATED CONTROL SYSTEM April 7, 1964 Filed Oct. 3, 1957 7 Sheets-Sheet 1 1 1g. 1 v FR REFERENCE FREQUENCY PR6 o (a Pl-I/ISE) 7v LOCAL CONTROLLERS QC-QQI/H 0f) VAR/ABLE 104?? g i FREQUENCY 106- l (3 PHASE) LQML CONTROLLERS :127

Fig '2.

(REFERENCE) 70 OTHER LOCAL COAUPOLLEES MASTER F'C (VAR/ABLE) CONTROL LEE LOCA L CON T POLLEE LOCAL. CON TEOLLE E Lc, e

Fig. 4a Fig. 4b

INVENTOR.

Fig 5 John L. BarKer.

ATT ORNE 1.

Fig. 4c Fig. 4d

April 7, 1964 J. 1.. BARKER 3,128,446

TRAFFIC ACTUATED CONTROL SYSTEM Filed Oct. 3, 1957 '7 Sheets-$heet 2 REFERENCE FRE UENCY (5 PHASE) LINES H A70 aTl-IER L LocAL 1 E EmNIRaLLERS M45 c VAR/ABLE FREQUENCY (a FHAsE) PHASE SHIFT/N6 'L/NEs To WHER FROM 1 LOCAL MAsrE/e 1 ..0N77?0LLEI?S i y W BY FORM/N5 NETWORK 31 a T2 j/VCREAS/NG} ,r-DRl t 77 VD 59 W2 70 CMC/DENCE I X GATE. 36 I 9; P

E 2 -1 k E 7/9 661 I I I M Q a I 66/ 3-: t k

l M 1" E; I g 99 1 J;-

g ,BVB 95 97 INVENTOR.

3 John L. Barker. 0 0

ATTORNEY- April 7, 1964 J. L. BARKER TRAFFIC ACTUATED CONTROL SYSTEM 7 Sheets-Sheet 3 INVENTOR. Joim L. Bar/fer.

#(L ATTORNE').

April v7, 1964 J. L. BARKER 3,128,446

TRAFFIC ACTUATED CONTROL SYSTEM Filed Oct. 5, 1957 '1 Sheets-Sheet 4 INVENTOR. 05/22? Z. Balk: BY wcad? AZ'ZURNEY SOQQ April 7, 1964 J. 1.. BARKER TRAFFIC ACTUATED CONTROL SYSTEM PI A INVENTOR.

John L. Bar/fer. BY

- ATTORNEY;

7 Sheets-Sheet 5 Filed Oct. 3, 1957 April 7, 1964 .1. L. BARKER TRAFFIC ACTUATED CONTROL SYSTEM 7 Sheets-Sheet 6 Filed Oct. 3. 1957 INVENTOR Ja/m L Barf. BY

ATTORNEY.

April 7, 1964 J. L. BARKER 3,128,446

TRAFFIC ACTUATED CONTROL SYSTEM 7 Sheets-Sheet 7 v 6 STREET B -----s Filed Oct. 3. 1957 'AGREEN-w INV ENT OR.

Ja/m LBar/(er.

F19 8 BY @MWZW ATTORNEY United States Patent 3,128,446 TRAFFIC ACTUATED CONTROL SYSTEM John L. Barker, Norwalk, Conn, assignor, by mesne assignments, to Laboratory for Electronics Inc., Boston, Mass, a corporation of Delaware Filed Oct. 3, 1957, Ser. No. 688,080 21 Claims. (Cl. 340-45) This invention relates to a traffic actuated control system and to a traffic signal controller for actuation by traffic in a master-local traffic control system in which a number of local controllers, each controlling the usual traffic signal or signals at an individual street intersection for example, are remotely controlled by a master controller as to some features of their time cycle for operation of the traffic signals in desired coordinated relationship to permit smooth flow of traflic through the several controlled intersections.

Various forms of traffic actuated control systems for individual intersections and groups of intersections are already well known in which the traffic signal time cycle is initiated or modified by actuation by the traffic itself, as are also a number of master-local traffic control systems in which the time cycle of the local controllers is supervised in several ways.

US. Patent 2,542,978, issued February 27, 1951 to John L. Barker, assignor to Eastern Industries, Incorporated, for Traffic Actuated Control Apparatus, illustrates certain forms of master-local control systems in which the total time cycle of the local traflic signal controller and its offset from a reference zero offset, and consequently its time lag or lead with respect to other local controllers, is remotely controlled by the master controller, with the master controller actuated by traffic at sampling points for varying the time cycle length and selecting among several offsets in accordance with traffie demand, for example. This prior patent also illustrates at least one way in which a traffic actuated local controller may be employed in such a master-local system.

The present invention relates particularly to a greatly improved local controller of the type adapted to be remotely controlled by a master controller and to be locally controlled by traffic actuation, as by cross traffic, as well as to a traflic control system of this type.

As far as the present local controller or traffic actuated system is concerned the master controller may be itself actuated by traffic for varying the time cycle length or offset or division or split of the right-of-way signal periods between through traffic and cross trafiic or other conflicting traific flows or intersecting streets, or these features may be changed on a program time basis of the master controller or otherwise remotely or by supervisory control, or such variations may be partly by master traffic actuation and partly by program timing, but the control of such variation by traffic actuation is preferred for greater flexibility, and the invention provides a greatly improved combination of local traffic actuated control, local time control and remote time control.

Thus in accordance with one aspect of the invention an improved trafiic actuated control system or local controller is provided with the traflic signal time cycle locally adjusted for distribution among several signal periods in desired percentage relation to a variable master controlled cycle and for desired offset relation thereto, and with one of the traffic signal right-of-way periods controlled by local traffic actuation within limits determined by such master control cycle.

The invention more particularly relates to a traffic control system in which individual local controllers of the semi-actuated type may have individually adjusted distribution of their time cycles or split of signal periods, as establishing limits for the periods as initiated or varied in accordance with trafiic demand by actuation, or several such individual splits with selection among such splits by remote control from the master controller, and with the total time cycles of the several local controllers determined and shortened or lengthened together by remote control from the master, while maintaining substantially the same percentage split of the cycle if desired for example. The invention also is adapted readily to the remote control of the offsets of the time cycles of the several signal controllers, and to a greatly improved method and means of changing offsets.

In its preferred form the traffic actuated controller or control system according to the invention is designed for operation in a master-local control system in which certain of the signal changes in the signal time cycle are controlled or initiated at desired percentage points in the time cycle variably controlled by the master controller or in desired offset relation thereto, and particulariy in such master-local control system in which the remote control of timing by the master controller is provided by very gradual progressive phase shift between a reference frequency and a slightly differing control or variable frequency to produce cyclic coincidences of the two frequencies at time periods of the order of the desired traffic signal cycle and by employing coincidence response means such as coincidence gate circuits in the local controller for obtaining the desired percentage control points in the signal cycle. The frequency difference is varied at the master controller as desired to vary the length of the signal time cycle at the local controllers.

In accordance with a further feature of such phase comparison system a local reference frequency element may be automatically rotated from one remotely selected and locally adjusted phase displaced relation to another such relation in response to change between such remote selections.

A traffic control system of the general type employing slow progressive phase shift between two electrical wave energies transmitted to the several local controllers and coincidence response thereto is the subject of a copending application S.N. 510,926, filed May 25, 1955, US. Patent 2,989,728, by John L. Barker, and reference may be had to said copending application for a more detailed description of certain features of such phase shift and phase comparison operation and system.

According to one aspect of the prior copending application S.N.- 510,926, a multiphase constant reference frequency and a multiphase variable frequency are both generated at the master controller, with the variable frequency derived from but having continuous gradual phase shift with respect to the reference frequency at an adjustable time rate, the time required for the variable frequency to shift one cycle with respect to the reference frequency corresponding to the desired total traffic signal time cycle for example, the variable frequency being variable in the sense that itis adjustable to the desired value of difference from the reference frequency for a desired signal cycle length but is constant at such adjusted value for such particular signal length.

The variable and reference frequencies are transmitted from the master controller to the several local controllers and at the latter these frequencies are applied to the stators of individual 360 degrees potentiometers, one potentiometer on each multiphase frequency circuit for example, and rotor arms providing adjustable position taps at degree spacing on such potentiometers take off voltages providing two sine wave outputs, one of which shifts its time phase with respect to the other slowly and uniformly at the desired rate of phase shift of the master controller.

These two sine wave voltages, each of single phase, one derived from the reference frequency and the other from the variable frequency, are applied to pulse form ing circuits to derive a sharp narrow pulse at corresponding points on their respective sine waves, such as at zero on the up-slope of the wave, for example, and the two pulses (one gradually and progressively shifting in time phase with respect to the other) are applied to a coincidence gate circuit to derive an output once per signal cycle at a particular point in the cycle as determined by the position of the potentiometer rotors. This coincidence pulse is then employed to operate a relay or other device to operate a particular signal or to switch signals in a signal cycle.

In a preferred embodiment of the present invention the coincidence of the pulses is employed in combination with traffic actuation to advance a cyclic stepping switch one step in a cycle of traffic signal indications, the stepping switch connecting one or more other response point potentiometers into the pulse forming and coincidence gate circuit at desired points in its step-by-step cycle to control certain signal switching or transfer points such as the maximum limit for the traffic actuated extendible right of way period of the cycle for example, and consequently to control the split or distribution of the signal cycle in accordance With the setting of the respective potentiometers.

According to a further aspect of the invention, by remote control of local relay circuits one of several potentiometers associated with the reference frequency may be selected to provide a desired offset or phase relation of the signal cycles, or remote selection between sets of variable frequency potentiometers may be made to select different splits, in association with traffic actuated control.

The invention is described particularly from its preferred aspects of providing both multi-phase reference frequency and multiphase variable frequency, and is illustrated in one preferred form in which both the reference frequency and the variable frequency are three phase, in order to provide the maximum of flexibility in deriving adjustable phase displaced voltages from one of these two frequencies to establish desired response points throughout the time cycle, and in deriving adjustable phase displaced voltages with respect to the other of the two frequencies to enable a desired phase displacement, or offset relationship in the case of traffic signal controllers, to be obtained for the entire time cycle. However, it will be understood that if these local controllers need not have an adjustable phase displaced relationship, as for example, if all of the time cycles are to be on a synchronized basis, with the local time cycles to have no phase displacement or offset with relation to the reference frequency, then such reference frequency need only be single phase rather than multiphase.

Although the control of transfer of right-of-way for a traffic lane by a combination of traffic actuation and a locally adjusted percentage point in a remotely controlled background cycle of variable time length is not itself new in general, there has long been a need for a more flexible and readily adjusted means for varying the percentage points in the background cycle at which the controller is to respond to actuation in initiating transfer of rightof-way and in establishing the desired offset of the local trafflc actuated control cycle with respect to the master control cycle.

Also in modern widely varying traflic conditions and rapid changes in such conditions particularly in connection with the morning and afternoon peak traffic periods and the preceding building up periods and in connection with shifts in such periods due to weather, special events and other changeable factors, it has become more important to provide a closer control of the retransfer of rightof-way from a traffic actuated crossroad to a main road for best coordination of the local intersection signal controller with others for through traffic movement for example, as the right-of-way for cross traffic is varied by traffic actuations.

Such closer control of retransfer of right-of-Way from the traffic actuated crossroad is provided on a new and much more flexible and readily adjusted basis in the present invention, to meet the varying demands of traffic.

Thus the present system or controller provides a positive control of the limit for retransfer of right-of-way at or in connection with a readily adjusted percentage point in the background cycle and provides for selection among three such individually adjusted percentage points.

The present invention provides such control in a novel and very flexible manner by combining traffic actuated control and background cycle control of the signal through means establishing joint cooperative control of certain signal changes or signal periods in the cycle by traffic actuation and by phase coincidence of two periodic wave energies having cyclic phase coincidences at remotely controlled time intervals by slow progressive phase shift, and by a wide range of adjustment and remote and local selection among multiple individual adjustments to which such means is readily adapted.

The greatly improved flexibility of control of the time cycle both by traflic actuation and by remotely controlled slow progressive phase shift between wave energies is provided by controlling a multi-position cyclic sequence switch at certain positions of its cycle mutually by traffic actuation and by phase coincidence of the remotely controlled and locally adjusted wave energies to achieve control of a right-of-way signal period in desired percentage relation to the remote controlled background time cycle.

It is an object of the invention to provide an improved traffic control system in which a number of local traffic signal controllers have a common total time cycle controlled from a master controller, with individual adjustment of the several signal periods of the time cycle and with the distribution and length of the several signal periods in the time cycle determined in part by traffic actuation at the local controllers and in part by the master controller.

It is another object of the invention to provide a traffic control system in which one or more local traffic actuated signal controllers have a traffic actuated signal time cycle controlled from a master controller within limits of a background cycle for desired coordinated traffic flow with selection by the master controller among individually adjusted offsets at the local controller, and with the time cycle of the local controller shifted gradually in the nearest direction to the new offset relation upon each change of selection.

It is another object of the invention to provide an improved trafiic control system in which a signal change in a local controller is controlled by a combination of trafiic actuation and phase coincidence between two periodic wave energies supplied from a remote master controller, one such wave energy being shifted progressively in phase relation to the other.

It is also an object of the invention to provide in a master control system having two periodic wave energies, one of which progressively shifts in phase with re lation to the other at a slow controlled rate, a traffic actuated signal controller providing a signal change in response to coincidence of a voltage having a predetermined phase relation to one of said wave energies and a voltage having a predetermined phase relation to the other of said wave energies.

It is another object of the invention to provide in a master-local traffic control system having two periodic wave energies, one of which progressively shifts in phase with relation to the other at a slow controlled rate, a traffic actuated signal controller causing a transfer of right-ofway from one traffic lane to another in response to a combination of trafiic actuation on said other lane and coincidence of a voltage having a predetermined phase relation to one of said wave energies and a voltage having a predetermined phase relation to the other of said 'wave energies, and setting a limit for retransfer of right-of-way from said other lane to said one lane in response to coincidence of a voltage having a further predetermined phase relation to said other of said wave energies and said first mentioned voltage.

It is another object of the invention to provide in a master-local trafiic control system having two periodic wave energies, one of which progressively shifts in phase with relation to the other at a slow controlled rate, a traffic actuated controller in which transfer of right-ofway from one traffic lane to another is controlled by a combination of traffic actuation and a predetermined phase relation of said wave energies.

It is another object of the invention to provide in a master-local trafiic control system having two periodic wave energies, one of which progressively shifts in phase with relation to the other at a slow controlled rate, a local trafiic actuated controller in which transfer of rightof-way from one traflic lane to another is controlled by a combination of traffic actuation and predetermined phase relation of said Wave energies with such predetermined phase relation being remotely selectable among a plurality of individually adjustable phase settings at the local controller.

It is another object of the invention to provide in a master-local traffic control ystem having two periodic wave energies, one of which progressively shifts in phase with relation to the other at a slow controlled rate, a traffic actuated signal controller in which transfer of right-of-way from one trafiic lane to another is controlled by a combination of traffic actuation and coincidence of wave energies having predetermined adjustable phase relation to the respective first mentioned wave energies.

It is another object of the invention to provide in a master-local traffic control system having master control of variable cycle length and selection among a plurality of locally adjusted offsets and splits for a local desired background cycle for coordination purposes, an improved local controller having a plurality of local adjustable percentage points for desired right-of-way signal changes in relation to the local desired cycle, and traffic actuated control of certain of such right-of-way signal changes at certain of said percentage points.

It is also an object of the invention to provide an improved traffic signal control system having locally or remotely controlled selection among a multiplicity of locally adjusted offsets and among a plurality of locally adjusted splits for a desired local background cycle of remotely controlled variable time length, and having trafiic actuated control of transfer of right-of-way in connection with a locally adjusted percentage point in such background time cycle associated with the selected offset, and in which retransfer of right-of-way is assured at or before a further locally adjusted percentage point in the background cycle associated with the selected split.

It is an additional object of the invention to provide an improved trafiic signal control system of the type last mentioned above in which the multiplicity of selectable offsets includes inbound, outbound, average and simultaneous offsets.

It is a further object of the invention to provide an improved traffic signal controller system of the type mentioned in the next but last preceding paragraph and which includes among the selectable offsets a non-coodinated or free offset or condition, permitting the local controller to act as an independent trafiic actuated controller.

Other objects of the invention will appear from the accompanying claims and from the following description of the invention with respect to the drawings in which: FIG. 1 illustrates in schematic form a master controller for a control system according to one embodiment of the invention.

FIG. 2 illustrates in block diagram form two of a series of intersections along a highway with individual trafiic signals and local controllers and connections with the master controller of FIG. 1 for example.

FIG. 3 illustrates in schematic circuit form and partly in block diagram one embodiment of a local tratfic actuated controller or system such as indicated applied to intersection A-B in FIG. 2 with connections for cooperation with the master controller of FIG. 1 for example and employing certain aspects of the invention.

FIGS. 4a through 4d, when arranged side by side as indicated in FIG. 5, illustrate in detailed schematic circuit form a preferred embodiment of a traffic actuated local controller or system for cooperation with a master controller of FIG. 1 for example and employing several aspects of the invention. The several drawings FIG. 4a, FIG. 41), FIG. 4c and FIG. 4d thus together form a circuit diagram which is sometimes referred to herein as FIG. 4 for convenience.

FIG. 5 shows how FIGS. 4a through 4d are to be arranged to form a complete circuit diagram.

FIG. 6 is a partly schematic diagram of an illustrative dial panel showing adjustment dials, selector switches and indicator lamps for the controller of FIG. 4 for example.

FIG. 7 shows schematically in block form a sample cycle of operation of the local controller of FIG. 4 in response to traliic actuation under coordinated control, with reference in parentheses to the dials shown in FIG. 6 above.

FIG. 8 shows similarly a sample cycle for free operation of the same controller in response to trafiic actuation, when operating independent of coordinated control. In considering the more detailed description below of the invention in relation to the several figures of the drawings it will be understood that in the timing of any given length of the time cycle, for traffic signal operation or for other purposes, in accordance with the invention, it is the period between successive phase coincidences of the two Wave energies derived from the master controller which is the important timing factor, and consequently the time rate of phase shift of one of these Wave energies with respect to the other determines the time cycle as controlled by the master controller. For any given time cycle length this rate of phase shift is constant, or in other words there is a constant frequency difference between the two frequencies of the respective two basic wave energies transmitted from the master controller to the local controllers supervised by the master controller.

If it is desired to change to a longer time cycle for the local controllers, then the frequency difference between the basic wave energies is decreased so that the rate of phase shift of one wave energy with respect to the other is decreased and the period between phase coincidences is thereby increased, to increase the length of the controlled time cycle.

Although such reduction of the frequencydiiference might be accomplished by increasing the frequency of the lower of the two frequencies and reducing the frequency of the upper of the two frequencies for example, it will be obvious that it is more convenient to keep one of the frequencies constant as a reference and to change only the other frequency, which thus may be considered a variable frequency or control frequency.

Thus for convenience of reference in: describing the invention one of the frequencies is assumed to be constant and is referred to as the reference frequency or reference periodic wave energy and the other adjustable frequency is referred to as the variable or control frequency or control wave energy, without intending that the invention shall be limited thereby.

For purposes of illustration and without limiting the invention thereof, the following values may be employed for the two basic periodic wave energies transmitted from the master controller to the local controllers. The reference frequency may be 400 cycles per second and the variable or control frequency may be adjustable from 400-{ 4 cycles per second to 400+ A cycles per second for a controlled time cycle adjustable between 40 seconds and 120 seconds in length, of the order of those widely used in traflic signals for street and road intersections, for example; and for a controlled time cycle of 60 seconds, the reference frequency may be 400 cycles per second and the control frequency 40O+ cycles per second or 400.0167 cycles per second approximately, for example.

For convenience of illustration the preferred form of the invention is described primarily from the viewpoint that the control frequency is higher than the reference frequency and consequently the reference frequency has a progressive lagging phase shift, or in other words a given point on the reference frequency wave travels slowly to the right with respect to a corresponding point on the control frequency wave, on a left to right time scale.

Referring now to FIG. 1, there is illustrated schematically one preferred form of master controller which may be employed in connection with one or more local controllers as illustrated in the remaining figures.

The three windings of an alternating current three phase generator are shown schematically at the left in FIG. 1 and designated FRG as a group, to indicate that this is the generator of the three phase alternating current constant reference frequency provided on the lines FR extending to the right and corresponding with the similarly desig nated lines of the other figures. These lines extend to the right of FIG. 1 for connection to the local controllers.

From these three reference frequency lines FR, a group of three branch lines extend downward to supply this three phase reference frequency to the input of a differential generator in block DG. This differential generator essentially adds or subtracts a small difference frequency to or from the reference frequency as desired to provide a new three phase frequency output differing so slightly from the reference frequency that the difference frequency amounts to a very slow progressive phase shift.

The differental generator DG is operated by a mechanical drive from variable speed motor VSM under control of the speed control SV, to vary the rate of progressive phase shift of the wave energy on lines PC with respect to the reference wave energy on lines PR and thus to vary the time cycle between successive phase coincidences of the two wave energies.

By making the variable frequency of lines PC from the reference frequency of lines FR by means of the differential generator, the reference frequency may drift in absolute frequency without upsetting the phase relationship of the variable frequency to the reference frequency, since the difference frequency remains the same as the differential generator is a phase shifter only.

Below the lines FR there is shown schematically the differential generator within the broken line box D6, and the lines FC extending outward to the right. For convenience in explaining the invention in connection with FIG. 1, the parenthetical designation (fc=fr+df) is noted along side of PC. This is intended as a reminder that the control frequency output on the lines PC is the sum of the reference frequency and the difference frequency corresponding to the rate of phase shift provided in the differential generator.

It will be understood that the usual 120 degree spaced three phase windings 101, 102 and 103 at the left of the differential generator DG as shown in FIG. 3 will have a rotating field, and for purpose of illustration this is assumed to be the stator set of windings. The windings to the right with the associated three curved arrows are also 120 degree spaced windings forming the rotor of the differ ential generator for example. The lines FC extend from these latter rotor windings 104, 105 and 1% toward the right, and correspond with the lines designated PC in several of the other figures of the drawings.

A variable speed motor VSM is shown schematically below the rotor windings of the differential generator and is indicated as mechanically associated therewith to drive the rotor by the broken line 107. The motor VSM is illustrated as connected via wires 108 and 109, and the variable speed control SV, to positive and negative electrical power terminals indicated. The speed control SV is illustrated as a potentiometer adjustable for controlling the voltage or power applied to the motor VSM to vary the speed of the latter as desired to obtain the frequency difference between the reference frequency and the variable control frequency.

It will be understood that the motor VSM has a low speed output, provided by gearing or otherwise as desired, to rotate the rotor windings 104, 105, 106 at speeds of the order of one revolution in 40 seconds to one revolution in 120 seconds to derive a time cycle of the order of 40 seconds to 120 seconds for example as described above, one revolution of the motor output shaft being equal to one time cycle of the system. It will be understood by those skilled in the art that when the three phase rotor windings are rotated with respect to the three phase stator windings of the differential generator DG the output frequency from the rotor windings for example will have a phase shift with respect to the input at the stator windings which progresses at a time rate depending upon the rate of rotation of the rotor. In effect the turning of the rotor in the direction of the rotation of the field at the three phase stator windings will provide a slightly lower output frequency in relation to the input frequency which may be expressed FC FR-DF for example, whereas if the rotor windings are turned in the direction opposite to the rotating field of the stator windings the output will have a slightly increased frequency which may be represented by the expression FC=FR+DF for example. For convenience in describing the invention it is assumed that the rotor windings always are turned in the same direction but at varying time rates to provide a variable time cycle for remote control purposes as described above.

In connection with the offset control lines in the lower part of FIG. 1, it will be noted that the switches SW1 and SW2 are connected at their left ends to the positive power terminal for example and are shown in a normally open position. The switch arm of either switch may be moved into its closed position independently to apply positive power to its associated line, the switch SW1 controlling line 0C1 and the switch SW2 controlling line 0C2, the remaining line 0C being connected as a common line to the negative power terminal. It will be understood that the power terminals designated plus and minus are merely for convenience of identification and may be direct current or alternating current power as desired. The lines 0C1 alone may be energized by the closing of switch SW1 and the line 0C2 may alone be energized by closing switch SW2 or both lines 061 and 0C2 may be energized by the closing of both switches.

As in the prior copending application above identified, the switches SW1 and SW2 provide control of or selection of offset between inbound, outbound, and average for example, at the local controllers over the lines 0C1 and 0C2. However, in the present application the simultaneous operation of local controllers at zero offset is provided not by the opening of both switches SW1 and SW2 as in the aforesaid copending application but by employing a third switch SW4 to energize an additional line SMl extending to the local controllers. Also, in the present application a fifth condition of non-coordinated or free operation of the local controllers as independent trafi'ic actuated controllers, is provided by the concurrent opening of switches SW1, SW2 and SW4. The switch SW4 is shown as connecting positive power via wire 110 to the switch to the line 8M1.

In the present application a more flexible form of control of the split of a traffic signal cycle is provided by having three locally adjusted split controls which may be cross-connected as desired with the offset controls as seleced from the master controller, as will be more fully described below in connection with FIG. 4.

The switches SW1, SW2 and SW4 may be manually operated as desired by the traffic authorities at the master controller location or may be operated automatically in the form of relay contacts from time switches or from an automatic offset selector system as indicated in prior Patent 2,542,978 referred to above.

Referring now to FIG. 2, there is shown in block diagram form two local controllers, LCI, a local controller of the non-actuated type, and LC2, a local controller of the semi-actuated type, at two intersections along a com mon through street A, and associated with the several sets of interconnecting lines extending from the master controller MC at the left. As in FIG. 1 the upper group of lines designated FR serve to carry the three phase reference frequency, the middle three lines extending from left to right designated FC carry the variable or control frequency, also three phase, and the lower four lines designated 8M1, C1, 0C2 and 0C serve as the offset control lines for example.

Along the lower part of FIG. 2 the common through street A is indicated as extending from left to right, with broken lines indicating that this street may extend further to other intersections in each direction and also indicating in the middle that the intersections may be much further apart than shown in the drawing. The intersection at the left has a crossroad or street designated B1 and the intersection at the right may have the crossroad designated as B, for example.

The traffic signals "[81 and T82, associated with the respective intersections, are shown schematically as circles in the center of the intersection, and may of course have any desired form or location in accordance with common practice. These signals TS! and TS2 are shown associated by lines llll and 112 respectively with local controllers LCl at the first intersection and LC2 at the second or right hand intersection. These local controllers are shown as connected with each of the three sets of lines on the master controller by groups of lines extending downward.

The semi-actuated controller LCZ has vehicle detectors VD and VD in the cross street B only, and has pedestrian pushbuttons PB on opposite sides of street A at street B. These detectors and pushbuttons may serve to actuate the controller to transfer the right-of-way to cross street B by means of the signal TS2 in desired relation to a background cycle for coordination with other controllers, as described in connection with FIGS. 3 and 4. The detectors and pushbuttons may also serve to extend the B street right-of-way period by further actuation up to a maximum limit, as described below in connection with FIG. 3, or the vehicle detectors may extend the right-of-way and the pedestrian pushbuttons provide a longer minimum right-of-way with walk" signals supplementing the usual green signals, as described below in connection with FIG. 4. The maximum limit is in each case determined in desired percent or phase relation to the background cycle when coordinated, as described in connection with FIGS. 3 and 4.

FIG. 3 illustrates one form of local controller associated with the reference frequency lines and variable frequency lines extending from the master controller of FIG. 1 to the several local controllers. The reference frequency lines FR starting at the left of FIG. 3 are extensions of the lines FR at the right of FIG. 1, and continue to the right across FIG. 3 for connection to other controllers as desired. Similarly the variable frequency or control lines PC of FIG. 3 are extensions of the lines PC of FIG. 1.

At the left side of FIG. 3 a group of three branch lines extend downward from the lines FR to supply the three phase reference frequency to three tapping points 120 degrees apart on the 360 degree continuous resistance forming the circular stator element of a 360 degree potentiometer PRZtl, dividing this stator element into three equal sections 21, 22, and 23. These three sections with their tapped connections to the three phase reference lines thus have a delta connected three phase arrangement as it is familiarly known in the electrical art, but with each section of the delta one third of a resistance circle.

The potentiometer PRZtl is provided with a two part diametric rotor having two contacts insulated from each other and movable jointly over the circular stator to any diametrically opposite contact positions, the contacts always being 180 degrees apart. The left hand arm 24, as shown is connected to an outer central contact ring and the right arm 25 of the rotor is connected to an inner central contact ring. These rings are in turn connected respectively by familiar contact brush arrangements via wires 26 and 27 to the input winding 31 of isolating transformer T2, the output winding 32 of which is connected to the input of a spike pulse forming network 33.

Since the rotor arms 24 and 25 of potentiometer PR20 provide movable taps 180 degrees apart on the delta three phase connected stator, these rotor arms will take off a single phase sine wave voltage from the three phase reference voltage on the stator, this single phase voltage being at the reference frequency and having a phase relation to the latter depending on the position of the rotor 2425. Thus by turning the rotor to the desired angular position, any desired phase displacement of the voltage output from the rotor can be obtained with respect to the original three phase reference frequency applied to the stator.

It will be noted in FIG. 3 that the rotor 25-24 is shown as slightly displaced counter clockwise from a position extending from the tap between sections 23 and 22 of the stator, to the opposite section 21 of the stator, as one illustration, and a dial plate-knob arrangement illustrated in FIG. 6 may be associated with the rotor 2425 to indicate the angle of phase displacement or percentage displacement on the basis of percent for 360 degrees of arm 25 with respect to the top center point as zero displacement, for example.

The single phase sine wave voltage, displaced from the reference frequency by the desired amount by potentiometer PRZQ), is thus applied via transformer T2 to the input at the top of the pulse forming network 33. This network is identified as a spike pulse forming network (as wave passes zero increasing) in its preferred form, of which one embodiment is shown and described in more detail in connection with FIG. 4:1. This spike pulse forming network derives a narrow spike pulse output at a particular point on the sine wave voltage applied to its input, this point being chosen for conveneince as the wave becomes positive just beyond zero. For convenience of reference this is considered as substantially as the wave passes zero increasing toward the positive peak. It will be appreciated that some other reference point might be selected within the spirit of the invention, but this point is employed in the preferred form of the invention.

The spike pulse output of network 33 is applied via line 36 to one of the two inputs to coincidence gate CGl.

In the middle of FIG. 3 are shown two additional potentiometers PR21 and PR22, which are of the same type as potentiometer PR20 described above, and have individually adjustable rotors set in different desired phase displaced relation as indicated for example, to determine desired percentage response points in the total time cycle controlled by the master controller via the reference frequency and variable frequency lines FR and FC. These percentage response points are employed to control signal changes in a traffic signal cycle according to one aspect of the invention as more fully described below.

The stators of the potentiometers PRZl and PR22 are connected in parallel in delta arrangement to the three phase variable frequency lines FC by the downward extending branch wires 41, 42 and 43, these wires being connected to corresponding tapping points on these two potentiometers respectively, spaced at 120 degree inter vals around the continuous resistance of each stator.

The two arm rotors of the two potentiometers have one contact arm connected with an inner ring and the other connected with an outer ring, as in P1129 described above, and the arm associated with the inner ring is considered to be the phase displacement indicator for convenience in describing FIG. 3.

The rotor arms, 44 and 45, are associated with the inner rings of potentiometers PR21 and PR22 respectively, and these arms are connected via the respective inner contact rings to individual contacts on the upper contact bank LS21 of a step-by-step selector switch, the opposite end arms of the respective rotors of potentiometers PR21 and PR22 and the associated contact outer rings being connected to corresponding individual contacts on the lower contact bank LS22 of this stepping switch respectively. The rotary contact wiper arms W21, W22, W23 and W24 of this stepping switch are associated with the respective contact banks L821, L822, LS2?) and L824, and are operated in ganged arrangement in clockwise rotation by the stepping switch motor magnet MM as indicated by the broken line 47 associating these several rotary contact arms with motor magnet MM. The rotation of these several contact arms is indicated by the curved arrows adjacent contact arms W21 and W22.

These several rotary contact arms W21, W22, W23, W24 and W25 are shown as single ended for simplicity of illustration, and similarly only live stationary contacts are shown on the associated contact banks, although it will be appreciated that additional contacts may be employed as needed and the rotary contact arms may be double ended or the like as desired to repeat the rotary traverse of the several successive stationary contacts beginning on the lowest contact position 1 as shown and continuing step-by-step to the uppermost fifth contact position shown and then directly thereafter to contact position 1 again, in which latter position the several rotary contact arms are shown in FIG. 3. The stepping switch operates only one step at a time in its cycle of contact positions upon each operation of its motor magnet MM, such operation including energization and release.

FIG. 3 is illustrated with the rotary contact arms W21, W22, W23, W24 and W25 in a rest position which may be called the street A green position.

Considering the several contact positions of the stepping switch and their connections in more detail in FIG. 3, the inner contact ring and associated rotor arm 44 of potentiometer F1121 is connected via wire 51 to position 1 contact on bank L521, and the opposite rotor arm and outer contact ring of potentiometer PR21 are connected via wire 52 to the corresponding position 1 contact of bank L522, and thus in the condition illustrated in FIG. 3 the potentiometer PR21 is connected via the contact banks L521 and L822 and the respective rotary contact arms W21 and W22 to control a second spike pulse forming network 53 and a second input line '8 of the coincidence gate CG1 as will be further described below.

Rotary contact arms W21 and W22 are connected respectively via wires 54 and 55 to the input winding 56 of isolating transformer T1. The output winding 57 of this transformer is connected to the input of the spike pulse forming network 53 and the output of the latter is connected as indicated by line 58 to the second input of coincidence gate (3G1.

The other input line 36 at the lower side of the coincidence gate CGl was previously described as controlled by the spike pulse network 33, which is in turn controlled by the output of potentiometer PRZtl. This coincidence gate C61 provides an output pulse on line 61 in response to the coincidence of pulses on the two input lines 36 and 55, to operate relay 62, which in turn by closing its contact 63, operates the stepping switch motor magnet MM. The other side of the relay 62 is returned to ground via contact BVl of the EV relay or DRl of the DR relay.

The contact BVIl of relay BV is open in position 1, however since the relay BV is energized only in No. 4 position. The relay DR will be energized to close its contact DR1 when the vehicle detector VD is closed by a vehicle crossing over the same. Assuming vehicle actuation, the relay DR is thus energized from plus power through its coil, the closed contacts of vehicle detector VD to ground. The relay DR locks in through its contact DR'Z, through lines 7% 71 to the stepping switch bank L825 through position 1, the wiper arm W25 to ground. The lock-in circuit of the DR relay will be completed in positions 1, 2, 3 and 5 of the stepping switch bank L525 to remember traffic actuation until accord of right-of-way in response thereto in positions 34. Thus upon energization of relay DR in position 1, the circuit of the coil of relay 62 is completed via wire 77 and contact DRl to ground and relay 62 will be energized in response to the output pulse of the coincidence gate CG1 via line er.

The contact 63 is normally open with relay 62 deenergized, but when relay 62 is energized by the output pulse from coincidence gate C61 as described, this contact closes to supply power, as indicated by the plus sign in a circle, via contact 63 and Wires o and 65 to motor magnet MM, the left side of this motor magnet being connected to the negative power return, indicated by minus in a circle.

It will be understood that if reference and control frequencies of the order of 400 cycles per second are used, a series of coincidence pulses will occur in the coincidence gate circuit at the 400 cycle rate throughout the brief time width of overlap of the two spike pulses as one shifts slowly in phase with respect to the other. However as more fully described below, the coincidence gate circuit provides a rectified and capacitance filtered output substantially sustained between the successive pulses of the series, and thus the relay 62 remains energized throughout the series during the brief period of substantial coincidence, which is preferably of the order of a fraction of a second for example.

Operation of relay 62 energizes motor magnet MM for this fraction of a second period of substantial coincidence of pulses from the spike pulse formers 33 and 53 and then releases this motor magnet MM as the coincidence or overlap of such spike pulses ceases to be sutficient to operate the coincidence gate, and the output pulse from the latter ceases. This operation and release of motor magnet MM advances the rotary contact arms W21, W22, W23, W24 and W25 from the lower position 1 to the next above position 2.

Thus as a result of traffic actuation of detector VD or VD on street B and consequent energization of relay DR, together with phase coincidence of the outputs of the potentiometers P1220 and PR21, one output having adjustable phase relation to the reference frequency and the other output having adjustable phase relation to the control frequency, the stepping switch has been advanced from position 1 to position 2 in its cycle in desired phase relation to the time cycle between coincidence of the reference and control wave energies from the master controller, and this advance of the stepping switch has occurred at a desired percentage point in the locally offset time cycle determined by the relation between the rotors of the potentiometers PRZtl and PR21, thus initiating transfer of right-of-way from street A to street B at such desired percentage point, as more fully appears below.

In this discussion the setting of potentiometer PRZd is considered the locally olfset zero reference for the percentage settings of potentiometer PR21 and P1122.

If there had been no actuation up to and including the time of operation of the coincidence gate at coincidence in position 1, the controller would remain in position 1 awaiting the next combination of coincidence and actuation at or prior thereto, but upon such coincidence and such actuation relay 6?. will be energized as described above to advance the controller to position 2 to terminate the A green signal period and to start the A yellow or clearance signal period.

The wiper arms of the respective rotary stepping switches are now in position 2 which position is timed by an interval timer calibrated in seconds, rather than percentage of the cycle. The timer here illustrated is a familiar resistance-capacitance type employing tube 75 and capacitor 74 to operate relay 76 at the end of its time interval to operate motor magnet MM to advance the stepping switch to its next position, as more fully described below.

Position 2 is the street A yellow or clearance position and position 3 is the street B initial green position as described below, the latter also being timed by the timer to advance the stepping switch to position 4.

Position 4 is the B street green vehicle interval position so-called, in which a short period timing of the order of several seconds may be reset by trafiic actuation to extend the time in this position and thus extend the B street right-of-way period up to a maximum limit established in a novel manner at a desired percentage point as described below.

Potentiometer PRZZ determines the percentage point in the time cycle at which the stepping switch will ad vance from position 4 to position 5 in the time cycle with relation to potentiometer PRZtl, as a maximum limit to such trafiic actuated time extension.

Thus the rotor arm 45 and associated inner contact ring of potentiometer PRZZ are connected via wire 66 to the fourth contact (in position 4) on bank L521, and the other arm of the rotor and the associated outer contact ring are connected via wire 67 to the corresponding fourth contact on bank L522. Thus in the position 4 of the stepping switch the potentiometer PRZZ is connected to the input of transformer T1 and thence via the pulse former 53 and line 58 for control of the coincidence gate CG]. in conjunction with potentiometer PR20, and therefore potentiometer PRZZ controls the percentage point in the time cycle in relation to potentiometer PRZt) at which the stepping switch is advanced from position 4 to position 5 by action of the coincidence gate through relay 62 operating the motor magnet MM. Relay 62 is operated in this case by positive power from coincidence gate CGll via wire 61, relay 62, wire 77 and branch circuit via contact BVl and Wire 89 to ground, the contact BVl being closed by relay BV being energized in this position 4 as described below.

Position 5 is a timed position for B street yellow or clearance for example and at the end of the timed period the stepping switch is advanced as before to the next position 1, from which the cycle was started.

Contact bank L524 of the stepping switch in FIG. 3 shows a group of signal lamps in the form of circles designated AG, AY, BG and BY connected with individual contacts or groups of contacts, as an example of one type of traffic signal cycle controlled in part by the master controller and in part by the local controller.

Thus as one illustration the signal lamps AG and AY, may be connected to individual contacts at positions 1 and 2, respectively, and lamp BG may be connected to adjacent contacts in positions 3 and 4, and lamp BY may be connected to the following contact in position 5. Power may thus be applied to these signal lamps in turn from one power terminal indicated as plus in a circle, via rotary contact W24 and the associated stationary contacts in turn on bank L524 as the stepping switch is advanced through its cycle, the left side of the several signal lamps being connected 1.4 via the common wires 72, 73 to the negative power terminal.

The several signal lamps AG, AY, BG and BY may represent the respective green go and yellow clearance signals for two intersecting roads A and B for example. Although the corresponding red stop signals are not shown, their inverse association with the green signal or with green and following yellow are so well known that their illustration here is omitted to simplify the drawing.

It will be noted that an additional contact bank L523 is employed in the stepping switch in FIG. 3. This bank and its associated connections to its left and below serve to illustrate how certain steps of the stepping switch cycle (and corresponding steps in the signal operating cycle of bank L524 for example) may be controlled by local timing so as to maintain a desired locally adjusted but preset time length while the total time cycle and the steps controlled by the percentage potentiometers vary in time length under control of adjustment of the time rate of phase shift by the master controller.

Thus the yellow signal periods are preferably of a constant length such as three seconds each, while the total time cycle may vary from 40 seconds to 120 seconds in length for example.

Similarly one part of a signal display period may be timed locally and another part timed on a percentage basis under control of the total time cycle by the master, as illustrated for example in the division of the BG display period into two time intervals on adjacent signal contacts 3 and 4 on bank L523 (in positions 3 and 4) of the stepping switch. Thus in this example the end of the time interval in the first of these positions (position 3) is controlled on a locally pre-set time basis previously described, the second of these positions (position 4) is also controlled on a locally preset time basis via contact bank L523 in part but is controlled on a percentage as a limit in addition.

The timing interval of position 4 dilfers from the timing interval of position 3 in that the time interval of position 4 is extendible by traffic actuation of detector VD during such interval, as described more fully below. Such extension of the time interval of position 4 is limited to a maximum period controlled on a percentage basis of the cycle by the potentiometer PR22. Thus the B green signal period may be terminated by the maximum percentage limit at coincidence or may be terminated by earlier completion of the timed period in absence of extending traflic actuation.

Obviously, within the scope or" the invention, the signal display period can be divided into further parts if desired, as with a timed part followed by a percentage part followed by another timed part as one example, by rearrangement of the contacts on the several contact banks in relation to signals and local timing control and percentage timing control, and more or all of the signal periods could be divided between the local timing and master controlled percentage timing.

Considering now the operation of the timing bank L523 and the associated timing units according to one embodiment of the invention as shown in FIG. 3, the timing is performed by a familiar method of charging a capacitor 74 slowly to the conduction voltage of gas discharge tube 75 to operate the time interval termination relay 76, the timing rate being varied as desired by control of the charging current by one of the several adjustable resistances 81, 82, 83 and 84, selected by the stepping switch.

These adjustable resistances 81, 82, 83 and 84 are connected via their adjusting taps for example, with individual contacts in positions 2, 3, 4 and 5 of contact bank L523 as shown, the left ends of these resistances being connected via a common wire 85 and common minimum or current limiting resistance 86 to a direct current power supply. Thus these adjusting resistances respectively are connected via rotary contact arm W23 in their respective 15 associated positions of the stepping switch via wire 87 to one side of capacitor 74, the other side of which is connected to ground for exampie.

The upper (positive) side of capacitor 74 is also connected via wire 91 to one side of gas discharge tube 75, the other side of the tube 75 being connected via wire 92 and relay 76 to ground. Thus when one of the adjusting resistances is connected via bank L523 in a desired position of the stepping switch, the capacitor is charged at the desired timing rate to conduction voltage of the tube 75, at which point the contained gas suddenly conducts to permit the capacitor to discharge through relay 76 to energize the latter and close its contact 96, which in turn connects power, from the terminal marked plus in a circle, via wire as to operate motor magnet MM to advance the stepping switch. As the motor magnet MM so operates, it closes its associated contact 94 to complete the discharge of capacitor 74 by connecting its upper side via wire 93, contact 94 and current limiting resistance 95 to ground.

It will be appreciated that other forms of timing might be used within the scope of the invention in relation to FIG. 3.

As previously stated, the preset time interval of position 4 is extendible and the extension of such time interval is obtained in a method well known in the art. Rotary stepping bank L525 is employed to complete a ground connection, through the wiper arm W25 and position 4 of the rotary stepping switch L525, wire 60 to the coil of relay BV to the power supply, thus energizing the relay BV.

Relay BV would close its contact BV2 and prepare a discharge circuit for the timing capacitor 74. If the vehicle detector VD contacts should close, due to a vehicle crossing over the same for example, the relay DR would become energized from the power supply, through the coil of the DR relay, wire the contacts of the vehicle detector VD to ground. The relay DR" would close its contact DR'3 thereby completing a discharge circuit for timing capacitor 74 from ground through resistor SR, contact DR3, contact BV2 wire 78 to wire 93 to the upper side of capacitor 74 thereby discharging the timing capacitor 74 to substantially zero with respect to ground. When the vehicle detector contacts VD reopen the relay DR would become deenergized and the contact DR'3 would open thereby breaking the discharge circuit so that the capacitor 74 would begin to recharge thus in eifect beginning a new time interval.

Should multiple timely actuations of the vehicle detector VD cause the capacitor 74 to discharge successively before the charge on the capacitor 74 approaches the breakdown potential of the flasher tube 75 so that the position 4 interval would be extended, the maximum timer as timed by the potentiometer PR22 would energize the relay 62, which circuit is completed from conicidence gate CGJl through the coil of the relay 62 through wire 77, contact BVl, wire 89 to ground.

With the relay BV energized its contact BVl, which would then be closed, would prepare a circuit to ground so that the relay 62 would be energized by power applied from the coincidence gate CGl at the proper percentage time in the cycle as determined by the potentiometer PRZZ.

With the termination of the preset time interval or the termination of the time interval based on the percentage of the cycle the motor magnet would be energized to advance the several wiper arms to the next position (position 5) of the rotary stepping switch.

Relay 62 and motor magnet MM cooperate, when energized in position 4 for the maximum limit, to energize relay DR. Relay DR is energized by ground via contact 97 of relay 62, wire 98, contact BV3 for relay BV and wire 99. Contact MM]. is adjusted to delay its opening to insure a ground connection for the lock-in memory circuit of the DR relay through contact DRZ wires 76 and 38, contact MM} to ground, as the wiper arm W25 advances from position 4 to position 5.

Should the time interval terminate with the termination of the preset time interval the relay 76 would be energized from the charged capacitor 74 via tube 75, wire 92, the coil of relay 76 toground. The relay 76 would closed its cont act 96 thereby energizing the motor magnet from the positive power supply through contact 9-6, wire 65, the coil of motor magnet MM to negative power.

Although in the illustrated rform of the invention of FIG. 3, locally timed steps are interspersed among the percentage timed steps controlled by the potentiometers PR2! and PR22, one or more of suchpotent-iometers might be used to provide desired operation at one percentage point only or at any desired number of such points in the time cycle, more or less than the two illustrated, within the teachings of the invention.

Although the control of the yield of right-of-way from road A to road B in response to traffic actuation on B is illustrated in FIG. 3 as determined at the desired percentage point in the background cycle for the local controller as established by the phase displacement of the adjustable potentiometer PR21, it will be understood that this potentiometer may be set at zero phase displacement with respect to its input from FC or the potentiometer may be replaced by a fixed potentiometer or potenial divider for deriving the single phase potential at a desired fixed phase relation as shown in FIGS. 4a-4d for example The pedestnain pushbuttons PB shown on opposite sides of street A in FIGv 2 at intersection B, to enable pedestrians to cross street A, are not shown specifically in FIG. 3. These pushbuttons PB may be connected in parallel with the vehicle detector switch VD and may be in the form of similar switches so that the switch VD may serve to illustrate either a vehicle detector switch or a pedestrian pushbutton switch in the simplified form of controller illustrated in FIG. 3.

However, as will be more fully described below in the preferred form of the controller of FIGS. 4a4d, the pushbuttons PB are illustrated as connected to a separate relay PD for pedestrians to control walk-Wait signals in association with the green signal of street B and to enable the pedestrians to have a longer crossing time than the minimum for vehicles alone.

It is preferred to have the flexibility of trafiic actuated time extension of the street B green period between the minimum time and the maximum percentage limits for most applications of the control, to enable the maximum band width of green for thru traffic on street A by permitting early retransfer of right-of-way to street A before the percentage limit on street B if it is not sufiicient on street B to prolong the right-of way on the street B to such maximum limit. However, it will be appreciated that in some applications it may be desired to have a uniform percentage of the cycle for street B in response to actuation so that whether there are one or more actuations the retransfer of right-of-way to street A will always occur at the percentage point established by the setting of the PR potentiometers, so that the street B green period would not in such case vary with trafiic actuation but would always terminate on the percentage point established by the coincidence gate operation. Such positive termination at the percentage point, without earlier termiation, can be provided if desired by disconnecting contact 97 and either adjusting potentiometer 83 for a longer time interval setting than the maximum percentage for example so that termination of B street green will always be on percentage as determined by operation of relay 62 by the coincidence gate, or similarly, such termination of street B green at a definite percentage point could also be provided if desired by disconnecting contact 97 and by opening the timing circuit in position 4, the potentiometer 8-3 for example.

Referring now to FIG. 4 which is composed of FIGS. 4a, 4b, 4c and 4d, arranged as shown in FIG. 5, this FIG. 4 shows a detailed schematic circuit diagram of a preferred embodiment of a local controller combining several features of the invention cooperatively in one systern, particularly adapted for operation in a traffic control system of the general type illustrated in block diagram in FIG. 2 and involving master control of the total time cycle for traffic signals for example, with master controlled expansion and contraction of the time cycle, master controlled change of split of the time cycle, and master controlled selection between several locally adjusted offsets of the individual local time cycles at the individual local controllers, and with smooth transition of the local time cycle from one such offset selection to another, the local cycle being partly distributed on a percentage basis by locally adjusted percentage potentiometers to expand with the total time cycle, and also involving local timing of the yellow or clearance signals, along with parts of other signal periods desired, so that the local timing of the several local controllers may be individually adjusted locally while being also jointly adjusted and synchronized by the master controller, and thus the local time cycle is controlled and timed partly from the master controller and partly from the local controller, all in cooperation with trafiic actuation at the local controller.

FIG. 4, here presented in four sections, FIGS. 4a, 4b, 4c and 4d, is illustrated in a rest position. The signals at the controlled intersection will show a green signal for go for vehicle trafiic on street A, a green walk signal for pedestrian to cross street B and a red signal for stop for vehicle traflic on street B with a red or wait signal for pedestrian to cross street A.

It will be assumed for the purposes of illustration that the local controller is in simultaneous offset operation.

FIG. 4 consists of FIGS. 4a, 4b, 4c and 4d, which illustrations comprise a complete circuit when arranged so that FIG. 4b is to the right of FIG. 4a while FIG. 40 and FIG. 4d are arranged under FIG. 4a and FIG. 4b respectively, all as shown in FIG. 5.

FIG. 4a illustrates three relays LO, S2 and S3 and their associated contacts below the respective relays, serving to control the selection of cycle splits. Relay LO serving to control the point in cycle at which splits may be changed, and is illustrated as energized, while relays S2 and S3 are illustrated as deenergized. Relays S2 and S3 select the local split adjustments under control of relay L and the remote oifset selection.

Below the contacts of the aforementioned relays is a group of three cycle percentage split adjustment potentiometer-s PRBl, P-RB2 and PRB3 of the types shown as PR22 in FIG. 3. Each potentiometer is associated with timing adjusting resistors TP1, TF2 and TP3, which are connected to a desired calibration point on a potential divider PDX at point PD The combination of potentiometer P RBl and resistor TPl affect split 1, while PRB2 and TF2, and PRB3 and TP3 affect splits 2 and 3 respectively. The block of resistors PRA from a potential divider immediately to the left of the potentiometers, serve to produce a voltage from lines FC phased to provide a zero reference point in a cycle, from which split percentage points in the local cycle may be obtained by adjustment of the potentiometers PRB1, PRBZ and PRES respectively, for remote selection.

The three horizontal lines marked PC are input variable frequency lines from the master controller, and correspond to the lines similarly labeled in FIGS. 1, 2 and 3. Immediately below the lines PC are three banks, A1, B2, and C3 of an eleven position, six bank rotary stepping switch, of the familiar telephone type, with the wiper arms W1, W2 and W3 with wiper arm W3 a bridged wiper. The additional contact banks D4, E5 and F6 and associated wipers W4, W5 and W6 are shown below in FIG. 40. Each wiper arm is illustrated in contact with position number 1 of its associated bank.

The motor magnet MM, located directly below bank C3, to the left of the diagram, with some of its associ- 18 'ated contacts, is used to advance the wiper arms of the several banks of the stepping switch step-by-step in a manner familiar to those in the art.

Additional adjustable timing resistors TF4, TPS, TF6, TF7 and TP'8 are found below the bank C3 of the rotary stepping switch with which the several timing resistors are associated, each being connected to a certain position on the bank C3 while the terminals marked PD+ are connected to a selected position on the potential divider shown in FIG. 40.

On the upper right of the diagram are six fixed terminals that may be in the form of insulated screw terminals, for example, and five adjustable forked terminal leads. The adjustable leads, which may be called offset leads for example, are connected to the desired fixed terminals, which may be called split terminals, for example. Any one or more offset leads may be connected to any spli terminal to obtain the desired split of the cycle during any selected offset operation of the local controller. These terminals are shown unconnected for convenience of illustration. It will be observed it the adjustable oiiset leads are not connected to any of the spli terminals or if the offset leads are connected to the two uppermost split terminals the split number 1 will be in efiect via back contacts of relays S2 and S3 as described below. It will be understood that the leads may be cross connected to the split terminals as desired.

Below the several terminals are the timing capacitor C10, flasher tube F10 and the relay ITR, with its associated contacts, which form part of the preset timing circui-t.

A selector switch CS, of the wafer type for example, is illustrated as having four possible positions, for difierent forms of operation of the controller. This switch is illustrated fully clockwise in an actuated and free position. However, by turning the three central elements of switch CS to the next position counter clockwise the actuated condition may obtained. The next position would provide pedestrian recall, while the fourth and last position places the local controller on vehicle recall, all as described more fully below.

The relay FOR is located below the selector switch CS. Relay FOR would be energized for free operation of the local controller but is shown deenergized in the condition assumed. The timing adjustment resistors TP9 and TP10 used during free operation are associated with several oi the contacts of the relay FOR.

FIG. 4b shows five relays OR, OR, IR, SIM, and PR with their associated contacts below the respective relays. On the upper right of the diagram are four lines OC, 0C1, 0C2, and SM1, which lines corresponding to the lines similarly labeled in FIG. 1. These lines are three offset selection input lines from the master controller 0C1, 0C2 and SMl and a common ground line DC from the master controller.

A selector switch SWltl-SWll is shown in its position 2 which position will cause the local controller to be in coordination with the system and also to provide simultaneous operation, when called for by the master controller.

If the selector switch SWltl-SWII were connected to position 1 the local controller would be in the coordinated system but not allowed to go into simultaneous operation. Position 3 of the selector switch SWIG-SW11 would place the local controller in isolated operation.

In the upper left of FIG. 4b are four indicator lamps of a neon type for example, which will be illuminated individually to indicate when the local controller is in free, outbound, inbound or average offset operation.

Switch SW11 is linked with switch SW10 and when switch SW10 is placed in position 3, switch SW11 will be placed in position 3 to supply a ground line to relay P-FR and thus placethe local controller in isolated operation, however PFR is deenergized with SW11 in position 2 as shown.

Four potentiometers PR4, PR5, PR6 and PR8 are associated with inbound orfset, outbound offset and average offset and simultaneous offset. Potentiometer PR7 provides the local reference wave energy for establishing the offset effective for the local controller. A reversible motor RDM is illustrated to the right of the potentiometers. The thru lines bracketed and labeled =FR are input variable frequency lines from the master controller, corresponding to those similarly marked in FIGS. 1-2.

FIG. 4c of the diagnam illustrates the remaining 3 banks D4, E5 and F6 of the eleven position 6 bank rotary stepping switch. Below the bank Fo there are illustrated nine relays AW, RR, GR, YR, WW, BW, PD, MR and DR with their associated contacts below each relay respectively. Relays AW and MR are illustrated as energized while the remaining seven relays of this group are illustrated as deenergized.

Ten circles below the relays illustrate signal lights of the conventional colors, green for go, yellow for caution or clearance and red for stop, plus pedestcrian walk and wait signals as desired.

In the lower section of FIG. 4c is a potential divider PDX made up of sevenal resistors with taps so that the several adjustable timing resistors may be connected to the desired tap from points PB+ on the timing potentiometer.

Two timing resistors T1 11 and TPlZ are also illustrated in FIG. 4c. A phantom form of the motor magnet MM is illustrated since its one contact is removed from the location of the motor magnet MM in FIG. 4a for convenience in the drawing.

The relays MMR and CR are illustrated with their associated contacts in FIG. 4c, and are shown energized and deenergized respectively. The button PB, associated with relay PD, represents a pedestrian pushoutton which is located externally as in FIG. 2 but is here shown nearby for convenience.

The vehicle detector VD, associated with the relay DR, is also illustrated nearby, for convenience, but is an external pant of this semi-actuated local controller, as shown in FIG. 2.

On the extreme left center of the diagram is selector switch SW12, which is an on/off switch which supplies power to illuminate the several traflic signals.

Near the right end of bank F6 of the rotary stepping switch is located switch SW13, which switch when in the position as illustrated, will cause the local controller to show an allsred signal when the stepping switch is in position 11. Should the switch SW13 be otherwise set the position 11 will become a skip position and the local con troller will substantially omit the all-red signal display.

FIG. 4d generally is a diagram of three pulse former networks PF 1, PF2 and PF3, arranged in a vertical column at the left, and three coincidence gate circuits CG1, CG2, CG3 and their associated output relays, MAX, R2 and R3 respectively arranged in a column at the right and each with its input at the left side and output at the right side.

These three pulse former circuits PFI, PFZ and PFS are indicated in general by the dashed line blocks so designated and are associated on their input sides with the respective transformers T1, T2 and T3 at the left, and the coincidence gate circuits CG1, CG2 and CG3 are similarly indicated by dashed line blocks and control the respective output relays MAX, R2 and R3 at the right. The pulse former of each horizontal row extends to the right of the output winding at the right of its associated transformer about one third of the way across the figure as indicated by the broken line block designated PFI in connection with the lowermost row, and the coincidence gate circuit is in general at the right half of each row as indicated in the broken line block designated CG1 for example in connection with the lowermost row, but the pulse former of each row is not necessarily associated 2h only with the coincidence gate of the same row, as will be described below.

In the intermediate vertical zone between the three pulse former blocks and the three coincidence gate blocks are certain cross connections between pulse formers and coincidence gates, and other connections as will be more fully described below.

The lowest of the three coincidence gate blocks, CG1 and its output relay MAX, is concerned at its output end with control of the stepping switch magnet MM (in FIG. 4a) and the advance of the stepping switch in certain steps as desired, such as steps 1 and 8.

The pulse former PF]; is concerned at its input end with the output of the potentiometers PRA, PRBl, PRB2, and PRB3, establishing the locally adjusted percentage points for the control of the advancing of the stepping switch at the desired steps in its cycle, in association with the control lines PC from the master controller, the output of pulse former PFll being supplied to the input of coincidence gate CG1.

The middle pulse former PFZ is concerned at its input end with the output of the potentiometer PR7 via transformer T2, the output of potentiometer PR7 serving as what might be called a local reference voltage, which in its normal stable condition on completion of its homing operation is in phase with the output of whichever one of the several potentiometers PR4, PR5, PR6 or PR8 is selected by remote control from the master controller, all of the several potentiometers just mentioned being associated with the reference frequency line FR.

As more fully described below the output from one of the potentiometers PR4, PR5, or PR6 is selected by operation of either one or both of the relays OR (and OR) or IR over the offset control lines 0C1, CO2 and OC from the master controller, or potentiometer PR8 is selected by the operation of relay SIM over the offset control lines 5M1 and DC from the master controller.

The reversible motor unit RDM in FIG. 4b is controlled by the outputs of the middle and upper coincidence gates of FIG. 4d to drive the rotor of potentiometer PR7 in FIG. 4b in the nearest direction at a relatively slow rate to coincidence of phase displacement with the one of the four potentiometers selected by the master controller to determine the offset of the local controller cycle.

Relays OR, OR and IR are for convenience shown deenergized with relay SIM energized indicating simultaneous offset demand as assumed, but it will be understood that relays OR and OR or relay IR, or both relays OR (and OR) and IR may be energized with relay SIM, and in most cases likely would be so energized, although this would not prevent simultaneous offset selection with relay SEM energized.

Relay OR is merely a contact multiplying relay for relay OR.

It will be understood that from the moment of change in offset selection by the master controller until the rotor of potentiometer PR7 has completed its rotation in its homing operation to coincide with the newly selected offset or phase relation, the output of potentiometer PR7 will be slowly changing in phase, and will be controlling pulse former P1 2 in FIG. 4d during such change as well as when at rest in its final position. The output of this pulse former PFZ will be applied to the input of the coincidence gate CG1 for comparison with the output of pulse former PFl to control the stepping switch in each desired percentage controlled point in its cycle. However, as more fully explained below, the output of pulse former PF2 is also applied to the coincidence gates CG2 and CG3 to control the homing operation of the rotor of potentiometer PR7 by means of the reversible motor RDM. In this connection the coincidence gate CG2 is employed to stop the motor at coincidence of the output voltage wave of PR7 with the output of the selected voltage wave of one of the potentiometers PR4, PR5, PR6 or PR8.

The output of pulse former PF2 is also applied to the input of the coincidence gate CG3, the output of which controls relay R3 which controls the direction of rotation of the reversible motor RDM, this being accomplished by phase comparison of the spike pulse output of pulse former PF2 with the square wave output of the pulse former PF3 of FIG. 4d, this latter pulse former having both a square wave output and a spike pulse output.

Reference may be had if desired to my aforesaid copending application for a more detailed description of this operation.

The operation of the controller through its cycle will now be described more fully in relation to the circuit in FIGS. 4a through 4d, such cycle being provided by the stepping of the stepping switch from position 1 through its 11 step cycle of positions and returning to position 1 to transfer right-of-way from street A to street B and retransfer right-of-way to street A.

As previously stated, it will be assumed that the local controller is in simultaneous operation and is at rest with a green signal illuminated for both vehicle and pedestrian traffic on street A and a red signal for both vehicle and pedestrian traffic on street B. It is further assumed that split 1 will be in elfect to control certain positions of the rotary stepping switch.

Simultaneous operation of the local controller is obtained when switch SW10 in FIG. 4b is in position 2 and the line SM1 from the master controller is energized while lines C1 and 0C2 are deenergized. Relay SIM would be energized from the input line SM1 thru the switch SW10, line 301 to the coil of the relay SIM to line 302 to ground.

Contact 303 would be closed to place a ground connection on the adjustable lead SIM, in FIG. 4a via line 304 while contact 305 would. be closed to complete a circuit to illuminate the indicator lamp SML from the alternating current power supply, represented by a plus in a circle thru line 310, indicator lamp SML, contact 305 of the relay SIM, line 308, contact 309 of the relay PFR to ground.

Contact 312 of the relay SIM completes a circuit from one of the input lines FR, through the potentiometer PR8, lines 316, contact 312, line 317 to the transformer T3, through the coil of the transformer T3 through line 318, contact 319 of the relay PR, line 320, contact 323 of the relay SIM, line 324 to the potentiometer PR8 to apply a selected adjusted phase input signal on transformer T3 with respect to three phase lines FR.

The output from the potentiometer PR7 is-applied to the input of transformer T2 via a circuit from the potentiometer PR7, thru line 325, contact 326 of the relay PFR, line 327 to the primary transformer T2, thru line 330, contact 331 of the relay PFR to the potentiometer PR7 via line 332 to apply a single phase voltage to transformer T2, the phase angle of which is adjustable with respect to the three phase lines FR by means of the reversible motor RDM through suitable gearing.

If a change of olfset to simultaneous has just now been called for by the master controller by operation ofrelay SIM the potentiometer PR7 will be in transition to the simultaneous offset condition for the local controllers, and will be driven by motor RDM gradually from its prior position of prior offset toward the new position matching in phase the simultaneous oifset in the nearest direction, thus speeding up or slowing down the actual local time cycle respectively for decreased or increased offset angle in the nearest percentage change direction. However, for purposes of the present it will be assumed that potentiometer PR7 has already reached its rest condition matching potentiometer PR8 for simultaneous olfset, with the time cycle of the controller matching the length of the master time cycle, i.e. the time spacing between phase coincidence between the wave energies on lines FR and FC.

When the local controller is at rest the wiper arms of 22 the several banks of the rotary stepping switch would be in position 1.

Wiper arm W1 of bank A1 in FIG. 4a connects the potential divider PRA, via line 333 to line 334 to the contact 335 of therelay FOR to line 339, through resistor R6, to line 41 to transformer T1, through the input of the transformer T1, line 342, resistor R7, line 347 to point 343, through line 349 to wiper arm W2 in position '1 of bank B2 to line 350 to the reference frequency line F01 from the master controller.

Wiper arm W4 in position 1 of bank D4 completes a circuit from the resistor 121 in the pulse former PFl in FIG. 4d through lines 351 to 352 to the wiper arm W4, position 1 of the bank D4, line 354 to contact 355 of the relay FOR to line 356, line 357, line 358, resistor R9 to line 236 to establish an operating bias for the grid 167 of tube in the coincidence gate CGl so that the tube 165 will be in condition to receive pulses from the pulse former PFl.

Wiper arm W5 in position 1 of bank E5 completes a circuit to energize the relay L0 in FIG. 4a fromthe power supply represented by a plus in a circle through line 361, the coil of the relay LO, line 362 to line 363 to position 1 of bank E5 to Wiper arm W5, line 447 to ground. A connection is also completed for the relay AW from the power supply represented by a plus in a circle, line 365, line 366, the coil of relay AW, line 367, line 36 8, line 363 to position 1 of the bank E5, wiper arm W5, line 447 to ground. A parallel circuit to illuminate the lamp 369 is also completed from the power supply, line 370, lamp 369, lines 364, 368 and 363 to position 1 of bank E5, wiper arm W5, line 447 to ground.

The relay L0 in FIG. 4a thus energized closes certain of its contacts to allow a change in split at this time. However, it is assumed for the present that no change in split will occur and split 1 remains in effect with relays S2 and S3 deenergized.

The relay AW closes its contact 374 to illuminate signal AGW, the green walk signal for street A which circuit is complete from the power supply, through switch SW12, line 375, line 376, contact 374 of the relay AW, line 377, signal AGW to line 378 to ground.

It will be noted here that relay MMR is normally energized by circuit from plus power via coil MMR, contact 518 of motor magnet MM to ground.

The signal AG, the green vehicle signal for street A, is also illuminated from the power supply through switch SW12,'line 375, line 381, contact 382 of relay RR, line 383, contact 334 of relay GR, line 385, contact 386v of relay YR, line 387 to signal AG, line 378 to ground.

The signal BR, the red vehicle signal of street B is illuminated from the power supply through switch SW12, line 375, line 388, contact 339 of relay GR, lines 393, 394, signal BR, line 378 to ground.

The BRW signal, the red pedestrian signal of street B, is illuminated from the power supply through switch SW12, line 375, contact 395 of relay WW, line 398, signal BRW, line 378 to ground.

The relay MR would also be energized at this time through a circuit from the power supply through the coil of relay MR, line 399, contact 404 of the MAX relay, line 405, line 406, contact 407 of relay DR, line 408, contact 409 of relay MR, line 412, contact 413, of relay PD to ground, which circuit is a lock-in circuit.

The rest condition of the local controller having been fully described, it shall now be assumed that the local controller has been at rest in the above described condition for an appreciable time. The pulse former PF1 and coincidence gate CG1 of FIG. 4d cannot energize the relay MAX because the cathode 213 of tube 205 is open at contact 414 of relay AW and contact 415 of relay MR of FIG. 40, so that the controller cannot leave position 1 until a traflic actuation of relay PD or relay DR releases relay MR to connect cathode 213 for operation at the next coincidence response.

Let us now assume that an actuation of vehicle detector VD on street B occurs by a vehicle approaching the intersection on street B. When contact VD closes, a circuit would be complete to energize relay DR from the power supply, through the coil of relay DR, line 416, contact VD to ground. When relay DR is energized the contact 407 of DR relay is opened to break the energizing circuit for relay MR as previously described so that relay MR would become deenergized and close its contact 415. Relay MR remains deenergized to remember the actuation because its lock-in contact 400 is open.

The circuit of cathode 213 in FIG. 4d would now be complete from cathode 213 through line 411, contact 415 of relay MR, line 417, line 418, point 419 on potential divider PDX, resistor 422 to ground.

With completion of the cathode circuit the tube 205 may now permit the coincidence gate CG1 to pass current to energize relay MAX in FIG. 4d. The relay MAX thus energized closes its contact 423 to complete a circuit to ground for motor magnet MM from the 12 volt power supply, indicated by a plus through the coil of motor magnet MM, lines 424, 425, 426, contact 423 of the MAX relay to ground.

The motor magnet thus energized would ratchet a stepby-step ratchet gear (not shown) and upon the motor magnet being deenergized, the ratchet wheel would be partially rotated to advance the wiper arms of the rotary stepping switch, in unison, to the next position 2. The deenergization of motor magnet MM would occur as the relay MAX is deenergized and permits its contact 423 to open and break the energizing circuit for the motor magnet MM as previously described.

The normal operating bias for grid 167 of coincidence gate tube 165 in FIG. 4d is available at arm 124 on po tentiometer 125, and this bias potential is connected via wire 133, resistor R9, wires 358, 357, contact 355 on relay FOR, wire 354, wiper W4, position 1 of bank D4, wire 352 to capacitor C11, as well as being connected via wire 351, resistor R121, wire 158 to the grid 167. Upon energization of motor magnet MM in position 1 as described above, its contact MM372 completes a circuit from ground via wire 373, resistor R30, to capacitor C11. This ground provides a cut-01f bias to grid 167 via its connection traced to capacitor C11. This terminates the coincidence pulses in tube 165 and thus cuts off the output of CG1 to the relay MAX to release the latter.

With the wiper arms in position 2 of the stepping switch, the wiper W1 of the bank A1 and the wiper W2 of the bank B2 are grounded, so that there is no input to pulse former PF1 of FIG. 4d. Positions 3, 4, 5, 6, 7, 10 and 11 are also grounded at these banks A1 and B2 to insure timing of the intervals via the pretimed timing potentiometers or resistors.

The wiper arm W3 of the bank C3, in position 2 connects the timing resistor TF4 connected at PD+ to a tap on the potential divider PDX so that a circuit is now complete from the direct current input, represented by a plus in a square, via the potential divider PDX at a point PD|, through the minimum resistor R10 to potentiometer TP4, tap 428, line 429 to position 2 of bank C3, Wiper W3, line 432, line 433 to charge the timing capacitor C10.

Position 2 of bank D4 completes circuit from resistor 121 in FIG. 4d through lines 351, 352, wiper W4, position 2, line 537, 358, resistor R9 to line 236. A similar circuit is also completed in positions 4, 5, 6, 9, 10 and 11 of bank D4, to keep bias on CG1, from operating in these intervals by having the input of PF1 shorted out.

The wiper arm W of bank E5 in position 2 breaks the ground connection for both relays L0 and AW, the circuits being previously described.

With the relay AW deenergized its contacts would be released to effect a change in signals. The green walk signal AGW for the pedestrian traffic along street A would be extinguished and the red wait signal ARW for 2.4 the pedestrian trafiic' along street A would be illuminated from the power supply through switch SW12, lines 375, 376, contact 434 of relay AW, line 435, signal ARW, line 37 8 to ground.

The interval now being timed would be preset and timed through the potentiometer TF4 so that when the charge on capacitor C10 approaches the breakdown potential of flasher tube F10, the tube F10 will pass current from capacitor C10 to energize the relay ITR. Energized relay ITR would close its contact 435 to supply ground connection for the motor magnet MM, to complete an energizing circuit from the direct current supply, through motor magnet MM, lines 424, 437, contact 436 of the relay ITR to ground.

The motor magnet MM would notch the ratchet (not shown) upon energization and would also close its contact 430 to discharge timing capacitor C10 through lines 433, 432, resistor R12, contact 438 of motor magnet MM to ground, thus reducing the charge on timing capacitor C10 to substantially zero.

With the charge on timing capacitor C10 so reduced, the passage of current through tube F10 stops and relay ITR is deenergized. The energizing circuit for motor magnet MM is broken with the release of contact 436 of the ITR relay, and the motor magnet becomes deenergized and advances the wiper arms of the several banks of the rotary stepping switch to the next position, position 3.

The position 3 is a skip position as are positions 7 and 9. The position 3 of bank E5 completes a circuit to ground for the motor magnet MM, through the line 447, wiper W5, position 3 of bank E5, line 539, line 534, contact 535 of relay MMR, lines 536, 425, 424, to motor magnet MM to ground. A similar circuit is completed through positions 7 and 9 of bank E5. Motor magnet MM is released to advance the stepping switch when its contact 518 opens the circuit to and releases relay MMR, which opens its contact 535 to open the circuit to MM. A second circuit through position 3 of bank C3 applies a rapid charge to timing capacitor C10 from DC. plus thru resistor R12, line 442, position 3 of bank C3, wiper W3 through the circuit previously described to rapidly charge capacitor C10 as a safety for the skip positions ,so that should the circuit through the bank E5 fail to complete a ground connection for the motor magnet MM the relay ITR will be energized to efiiect energization of motor magnet MM.

The motor magnet advances the wiper arms to the next position (position 4) of the stepping switch as previously explained.

While in position 4, bank E5 completes an energizing circuit for relay YR from the input supply through line 365, the coil of the relay YR, line 445, line 446 to position 4 of bank E5, wiper W5, line 447 to ground. The green signal AG is extinguished via open contact 306 of relay YR, and the yellow signal AY, the street A clearance signal, is illuminated from the input supply through switch SW12, line 375, line 331, contact 332 of relay RR, line 383, contact 384 of relay GR, line 385, contact 448 of relay YR, line 449 to signal AY, line 378 to ground.

The interval, timed through the wiper arm W3 of bank C3, is timed by charging capacitor C10 from PD+ through timing potentiometer TF5, and its minimum resistor below, line 444 to position 4 of bank C3, wiper W3, and the circuit previously described to timing capacitor C10. At the termination of the interval the wiper arms are advanced to the next position (5) as previously described.

In position 5 the relay GR is energized from input power through line 365, the coil of relay GR, line 463, line 465, line 466 to contact 457 of relay BW, line 468, line 460 to position 5 of bank E5, wiper arm W5, line 447 to ground.

The red signal AR for vehicle traflic on street A would now be illuminated and the yellow signal AY would be 25 extinguished. The signal AR would be illuminated from input power, through switch SW12, line 375, line 388, to contact 472 of GR relay, line 473, line 474 to signal AR, line 378 to ground.

The red signal BR is extinguished and a green signal BG for vehicle traific on street B is illuminated from input power, through switch SW12, line 375, line 381, contact 382 of relay RR, line 383, contact 475 of relay GR, line 476, contact 477 of relay YR, line 478 to signal BG, line 37 8 to ground.

In the absence of a pedestrian pushbutton actuation, as has been here assumed, the position becomes a skip position since a circuit is complete from ground, through wiper W6, position 5 of bank F6, line 553, contact 563 01 relay BW, lines 564 and 534, contact 535 of relay MMR, line 536, line 425, line 424 to motor magnet MM to the power supply thereby immediately energizing motor magnet MM. The motor magnet MM Opens its contact 518 to release relay MMR to release motor magnet MM to advance the several wiper arms as previously explained to position 6.

With the wiper W3 of bank C3 in position 6 an initial interval would be timed for vehicles on street B, timing potentiometer TP11, in FIG. 40, by charging timing capacitor C10, in FIG. 4a from PD+ through potentiometer TP11 and its associated minimum resistor, line 483, contact 484 of relay BW, line 485, to position 6 of bank C3, wiper W3, and to timing capacitor C as previously described.

A parallel circuit through position 6 of bank F6 and wiper W6 now completes the energizing circuit for relay GR along with the circuit previously described.

When the timing capacitor C10 becomes sufficiently charged the flasher tube F10 will pass current and effect the advance of the wiper arms to the next position (position 7) as previously described.

The position 7 is a skip position similar to position 3, and actions similar to those described with reference to postion 3 take place except that the wiper arms are in position 7.

The wiper arms are advanced to position 8, during which interval, the timing capacitor C10 of FIG. 4a is charged through the timing potentiometer TF6 from PD+ through TF6, line 486, to position 8 of bank C3, to wiper W3 to timing capacitor C10 as previously described. The vehicle interval timing circuit just described is an extendible interval, which is extended by traffic actuation of the vehicle detector VD during such interval as explained below.

While the resettable vehicle interval timer is connected as previously described, a maximum limit control circuit is also connected in position 8 through banks A1 and B2, which determines the extension limit of street B green on the basis of a percentage of the cycle, controlled by the split in effect at the time. Here it has been assumed that split 1 is in eifect so that potentiometer PRB1, of split 1 would control the percentage basis. The input of potentiometer PRB1 is connected to the three phase reference frequency lines PC from the master, and the output of potentiometer PRB1, of a single phase voltage is connected through line 487, contact 488, of relay S2, line 489, contact 493 of relay S3, line 494, to poistion 8 of bank A1, wiper W1, line 334, contact 335 of relay FOR, line 339, resistor R6, line 341, to transformer T1 primary, line 342, resistor R7, line 347, to point 348, line 349, to wiper arm W2 of bank B2, position 8 of bank B2, line 495, to contact 496 of relay S3, line 497, contact 498 of relay S2, line 499 to potentiometer PRB1.

The bank D4 completes a circuit from resistor 121 in pulse former PFI in FIG. 4d, through lines 351, line 352 to wiper W4, position 8 of bank D4, line 503, contact 504 of relay FOR, line 505, line 357, line 358, resistor R9, to line 236 in FIG. 4d to establish an operating bias for the grid 167 as previously described.

The position 8 of bank E5 completes. a circuit to enervgize the relay CR in FIG. 4c from the power supply,

through the coil of relay CR, line 506, position 8 of bank E5, wiper W5, line 447 to ground.

When the relay CR is energized its contact 507 is closed to complete an energizing circuit for relay MR in FIG. 4c from the power supply, through the coil of relay MR, line 399, contact 404 of relay MAX, line 405, to contact 507 of relay CR, line 508, contact 509 of relay MMR to ground.

With the relay MR energized, a circuit is prepared through its contact 513 to discharge capacitorC10 if an actuation of the vehicle detector VD should occur during the presently timed interval. Assuming such an actuation did occur, the contact VD would close to complete an energizing circuit for relay DR as previously described.

When energized, the relay DR would close its contact 516 to complete the prepared discharge circuit for the capacitor C10, from the upper side of this timing capacitor, through line 433, line 515, resistor R24, contact 516 of relay DR, line 517, contact 513 of relay MR to ground, thus reducing the charge of the capacitor to substantially zero for example, for resetting its timing.

With the passage of the vehicle across the vehicle detector VD, the contacts VD would then reopen and open the energizing circuit of relay DR. Thus contact 516 of relay DR would reopen and break the discharge circuit of timing capacitor C10 so that the timing capacitor C10 would begin to recharge to retime this vehicle interval.

Subsequent actuation of the vehicle detector VD would cause additional discharging of the timing capacitor C10 so that the time in the B green position 8 may be extended. In the absence of actuations on the vehicle detector, or if the actuations are suificiently far apart, the timing capacitor C10 will charge sufiiciently to reach the breakdown potential of tube F10 so that the charge on capacitor C10 will pass through the tube F10 and energize the relay ITR, to effect the advance of the stepping switch to its next position 9.

However, if multiple actuations of thevehicle detector should keep capacitor C10 from becoming charged to the breakdown potential of the tube F10, then the maximum limit control will terminate the interval at the predetermined percentage point of the cycle, set by the potentiometer PRB1. The output of the potentiometer PRB1 would be applied to the pulse former PF1, while the output of potentiometer PR7 would be applied to the pulse former PFZ, and compared in coincidence gate circuit CG1. At, the predetermined percentage point of the cycle, determined by the coincidence gate CG1 would pass current to energize relay MAX. Relay MAX would close its contact 423 to complete a ground connection for motor magnet MM as previously described. The relay MAX would also open its contact 404 to break the energizing circuit for the relay MR to release MR to leave a vehicle call for return of right-of-way to street B in the next cycle.

Relay MMR would also be deenergized as the motor magnet MM opened its contact 518.

The return circuit of cathode 213 of tube 205 in CG1 was completed in position 2 over contact 414 of relay AW. This circuit extends from cathode 213 via line 411, line 416, back contact 41-4 of relay AW (which was released in position 2), line 418 to junction 419 on potential divider PDX near ground to provide normal operating bias for the tube 205. This cathode return circuit remains completed until the rest position 1. is reached at which time relay AW is operated to open its contact 414, and at which point the cathode return circuit becomes dependent on closure of parallel circuit via contact 415 of relay MR.

In the present case it was assumed above that the B green interval was terminated by the MAX relay on the percentage maximum limit, thus having relay MR deenergized. 

21. IN A TRAFFIC CONTROL SYSTEM, MEANS FOR PROVIDING TWO PERIODIC ELECTRICAL WAVE ENERGIES, ONE OF WHICH IS SHIFTING PROGRESSIVELY IN PHASE RELATION TO THE OTHER AT A CONTROLLED SLOW TIME RATE TO PROVIDE PHASE COINCIDENCES AT TIME INTERVALS OF THE ORDER OF THE DESIRED TRAFFIC SIGNAL TIME CYCLE, TRAFFIC ACTUATED MEANS FOR RESPONDING TO TRAFFIC, COINCIDENCE RESPONSIVE MEANS FOR RESPONDING TO PHASE COINCIDENCE OF SAID TWO WAVE ENERGIES, AND MEANS FOR CONTROLLING A TRAFFIC SIGNAL CHANGE IN RESPONSE TO CONJOINT OPERATION OF SAID TRAFFIC ACTUATED MEANS AND SAID COINCIDENCE RESPONSIVE MEANS. 